Revert "Update to Mono 5.8"
Revert "Update to Mono 5.8"

This reverts commit c04b0c986f0395a1cc60b6c6b2d7c5b48ce19e21.

QuantConnect/Lean,Jay-Jay-D/LeanSTP,JKarathiya/Lean,AlexCatarino/Lean,Jay-Jay-D/LeanSTP,StefanoRaggi/Lean,StefanoRaggi/Lean,kaffeebrauer/Lean,AnshulYADAV007/Lean,JKarathiya/Lean,StefanoRaggi/Lean,kaffeebrauer/Lean,AlexCatarino/Lean,QuantConnect/Lean,AlexCatarino/Lean,redmeros/Lean,AnshulYADAV007/Lean,AnshulYADAV007/Lean,jameschch/Lean,kaffeebrauer/Lean,AnshulYADAV007/Lean,StefanoRaggi/Lean,QuantConnect/Lean,Jay-Jay-D/LeanSTP,kaffeebrauer/Lean,redmeros/Lean,StefanoRaggi/Lean,JKarathiya/Lean,redmeros/Lean,jameschch/Lean,QuantConnect/Lean,AnshulYADAV007/Lean,jameschch/Lean,kaffeebrauer/Lean,jameschch/Lean,Jay-Jay-D/LeanSTP,JKarathiya/Lean,AlexCatarino/Lean,redmeros/Lean,Jay-Jay-D/LeanSTP,jameschch/Lean